This project is concerned with investigating (1) the structural specializations underlying aqueous humor production in the ciliary epithelium; (2) the anatomical devices which control aqueous humor outflow at the sclero-corneal angle; (3) the morphological basis of the blood-aqueous barrier, (4) and its experimental manipulation with paracentesis, systemic administration of hypertonic agents or prostaglandins. Freeze-fracturing and ultrastructural tracers represent the experimental probes. The precise knowledge of the anatomical mechanisms which regulate the intraocular pressure is necessary for a better understanding of the pathogenesis of glaucomas and for devising new pharmacological methods for their control. BIBLIOGRAPHIC REFERENCES: Raviola, G.: Penetration of a blood-borne tracer into the eye chambers by lowering intraocular pressure. Abst, Anat. Rec. 184: 593, 1976. G. Raviola: Intercellular junctions in the fenestrated vessels of the uvea. ARVO 1977, in press.